It is known to use breathing films for the manufacture of shoes or gloves. The purpose of these films is to impart a pleasant feeling to the wearer, because, on the one hand, they permit the transport of water vapor, so that body fluid such as sweat, after evaporation from the skin, can be dissipated to the environment through the film. On the other hand, these films are intended to be impermeable to liquid water, so that rain, for example, cannot pass to the skin through the shoe or glove. In other words, said breathing films must be impermeable to water and permeable to water vapor. They can then be utilized as interlayer for shoes or gloves, which also possess an outer layer and an inner layer, each of which may, for example, consist of leather or fabric. Films of this type and shoes or gloves that contain such films are described, for example, in West German Laid-open Applications 2,737,756, 3,147,202, U.S. Pat. Nos. 4,520,056, 4,545,841 and 4,679,257.
Among the disadvantages in employing such films is the fact that, for ease of handling and the necessary mechanical strength, they must have a certain minimum thickness. Very thin films cannot be used, since the stretching and shearing load in shoes or gloves requires a certain mechanical strength which is achieved only if the thickness reaches a certain minimum. The use of films with a particular minimum thickness, on the other hand, makes the article more expensive, since the breathing films constitute a cost factor that cannot be disregarded in the finished article.
Furthermore, the transport of water vapor to the environment is slowed down if the film thickness is relatively great.
Attempts have been made to overcome said disadvantages by employing laminates consisting of breathing film and unwoven fabrics, such as, for example, heat-bonded fleeces. This is, for example, described in U.S. Pat. Nos. 3,510,344, 3,713,938 and 4,594,283. The disadvantages in using such laminates for the manufacture of shoes or gloves lie in the fact that the unwoven fabrics such as, for example, fleeces, have only low stretchability so that the laminates cannot be bonded and formed in one piece with the outer layer of shoes. In this case, the problem is the same as with laminates containing fabrics consisting of fully stretched threads. This will now be described in detail hereinafter.
Laminates consisting of breathing films and woven and knitted fabrics have already been employed in the past. This is apparent, for example, from European Patent A 0,110,627, British Patent A 2,114,583, U.S. Pat. No. 4,599,810, West German Laid-open Application 2,737,756 and West German Laid-open Application 3,149,878. In all these cases, the woven or knitted fabrics consisted of fully stretched synthetic yarns or filament yarns. The disadvantage of these laminates is their relatively low stretchability. This has a disadvantageous effect on the manufacturing process during the fabrication of shoes or gloves. Since these laminates have only poor stretchability in the longitudinal and transverse directions, they must be cut to size in individual pieces and bonded with matching pieces of the inner layer. These pieces are then stitched together and the whole is bonded with the prefabricated, formed, one-piece outer layer, e.g., by adhesion. Thus, the manufacture of shoes or gloves not only becomes expensive, but the seams with which the individual parts consisting of laminate and inner layer are bonded together form, in the finished article, weak spots through which water can penetrate. Therefore, it is frequently necessary to waterproof these seams for example, by using sealant or seam-waterproofing tapes.